What's Up?

January 1 - January 7, 2007




SUMMARY: Greetings, fellow SkyWatchers... Welcome to the new year and 365 more nights with you! Thanks to everyone for their kind words about the new edition and how great the softcover book turned out. The sky is nt the limit as we begin 2007 exploring the Moon and keep on reaching for the stars. Now, let's head out into the night because...

Here's what's up!

Monday, January 1 - Greetings, fellow SkyWatchers! We start our observing evening with the beautiful Moon and an opportunity to practice some selenography. In binoculars or small telescopes, one of the most prominent features will be the ancient and graceful Gassendi standing at the north edge of Mare Humorum. The mare itself is around the size of the state of Arkansas and is one of the oldest of the circular maria on the visible surface. As you view the bright ring of Gassendi, look for evidence of the massive impact which may have formed Humorum. It is believed the original crater may have been in excess of 462 kilometers in diameter, indenting the lunar surface almost twice over. Over time, similar smaller strikes formed the many craters around its edges and lava flow gradually gave the area the ridge- and rille-covered floor we see tonight. Its name is the "Sea of Moisture," but look for its frozen waves in the long dry landscape.

On this night in 1801, the skies were clear in Italy and astronomer Giuseppe Piazzi had just made a discovery - what would eventually become the first known asteroid. Unlike today's instant communications, Piazzi had to relate his observations to others via the mail - but by the time they received it, his discovery had moved too close to the Sun and was lost. What we now know as minor planet Ceres was not relocated until it returned in September of that same year. With some help from Gauss and his method of calculating orbits, Ceres was identified again on the last day of 1801 and reconfirmed again on this date in 1802. While Ceres isn't safely visible tonight, you can try your hand at another bright asteroid, Iris, which is well placed right now in the constellation of Aries.

Tuesday, January 2 - In 1959, the USSR launched the very first Moon probe. Named Luna 1, it became the first extraterrestrial spacecraft. The spacecraft carried no propulsion system of its own, but after having reached escape velocity, its third stage released a payload of sodium gas, which left a glowing trail that reached a brightness of sixth magnitude, allowing astronomers to trace it. Luna 1 made outstanding contributions to science, including the first confirmation that the Moon had no magnetic field. The probe was designed to impact the surface, and although it failed to do so, it did achieve another first with its flyby.

Tonight turn your eyes towards the Moon as we perform a "flyby" of our own and identify a feature known as the "Cow Jumping over the Moon." It is strictly a visual phenomenon - a combination of dark maria which looks like the back, forelegs and hindlegs of the shadow of that mythical animal. It's not only fun, but an Astronomical League Lunar Challenge as well! If you're up for another challenge, then it's time to identify the Oceanus Procellarum - the Ocean of Storms. Like many mythically based astronomy names, Oceanus Procellarum came from a superstition associated with its appearance. Once upon a time, it was believed that sighting this feature precluded bad weather, but backyard astronomers know it only forecasts the coming Full Moon. Formed by volcanic eruptions, this largest of all maria is little more than an expanse of long hardened magma stretching from north to south a distance of around 2500 kilometers. Although to the eye it may seem featureless, it is home to some very unusual features and some historic missions that we will study in the future.

Wednesday, January 3 - Tonight is the Full Wolf Moon. Its name comes from the North American Indians who would hear the wolves howling in search of food in the snow-covered, cold and barren landscape. In Europe it was referred to as the Moon after Yule.

Today is the birth date of Russian astronomer Grigori Neujmin (1886.) His important discovery was the rotating asteroid Gaspra. This is also the date that Stephen Synnot discovered Juliet and Portia, two additional moons belonging to Uranus.

Although skies will be bright, be sure to keep a watch for members of the Quadrantid meteor shower. Its radiant belongs to an extinct constellation once known as Quadran Muralis, but any meteors will seem to come from the general direction of bright Arcturus and Bo÷tes. This is a very narrow stream, which may have once belonged to a portion of the Aquarids. As Jupiter's gravity continues to influence it, in another 400 years of so this shower will become as extinct as the constellation for which it was named.

Thursday, January 4 - Tonight the Moon will look nearly full and it is a good time to spot yet another lunar asterism, "The Rabbit in the Moon." While it is nothing more than a compilation of dark maria, look for the long expanse of Mare Frigoris which creates the rabbit's "ear." Maria Serenitatis, Tranquillitatis, Nectaris and Fecunditatis will form the hindquarters and legs, while Oceanus Procellarum and Mare Humorum denote the head and forelegs. All rabbits have a tail, so be sure to look for Mare Crisium!

Today is also the birthdate of Wilhelm Beer (1797), an amateur astronomer who with Johann Madler created an exhaustive and first of its kind map of the Moon - Mappa Selenographia. Tonight discover for yourself what Galileo and Beer saw. Using any type of optical aid, trace the bright lunar rays extending from the brilliant Tycho or the deep impact crater Copernicus.

But, if you hear a wolf howl...perhaps it might be the "Dog Star" on the rise. Alpha Canis Majoris, better known as Sirius, is the fifth nearest star known and has played an important role throughout the history of astronomy. Although Sirius is a "moving star," belonging to the Ursa Major moving group, there is historical evidence that it was seen from the island of Zylos in the Persian Gulf on the 29th of April - in the year 11,542 BC!

Watch its dazzling appearance while it is still fairly low and flashing all colors of the rainbow. The light you see from this main sequence star left almost 9 years ago and was seen by Ptolemy, Homer and Plutarch. The ancient Egyptians revered it and the Greeks and Romans feared it. Enjoy it tonight and we'll be back to study...

Friday, January 5 - With very little time before the Moon rises tonight, let's turn our attention towards the constellation of Orion and a binocular and small telescope cluster known as Collinder 69. While many of us have looked at Orion's triangular head before, what we may not have realized is that the area surrounding third magnitude Lambda is an open cluster. Containing approximately 19 stars that range from fifth to ninth magnitude, look for a southward extending chain that gives this collection its signature.

As you look at the brightest star, let me introduce you - its name is Meissa. The cluster itself is considered young, and probably formed no more than 10 million years ago. On a dark night, look again to see if you can spot some nebulous filaments that remain from its birth! Now look at Orion's belt. Almost all of us have seen these three stars time and again, but did you know they are also part of an open cluster?

Turn your binoculars there and have a look. In an area spanning about three degrees are around 100 stars known as Collinder 70. Look for many mixed magnitudes, chains and pairings. This area has been used in the search for brown dwarfs!

Saturday, January 6 - Today in 1949, the first atomic clock built on theoretical work by Isidor Rabi and Norman Ramsey went into operation. This model used ammonia as its "pendulum," but only 8 years later the first cesium beam device was built. Clocks using this primary standard are now keeping time to about one-millionth of a second per year. Like clockwork, objects that we can view also keep incredibly accurate time. Tonight return again to Orion's belt as we have a closer look at its westernmost star - Mintaka.

Located around 1500 light-years away, Delta Orionis usually holds a magnitude of 2.20, but orbiting it in a clockwise orbit of 5.7325 days is a nearly equal star around 8 million kilometers away. Mintaka is a prime example of an eclipsing binary star, and although visually you won't really notice a .2 magnitude drop in light, let's take a closer look with binoculars.

As one of the few easy binocular double challenges, Mintaka will easily reveal its 6.7 magnitude companion star to its north. For over 100 years, the eclipsing physical AB pair has been closely watched and no movement between the half light-year apart physical pair has been detected. For those with larger telescopes - power up - and see if you can discover the 13th magnitude C star southwest of the primary.

No matter how you look at Mintaka, this fascinating star has been a part of history. It was the very first to display stationary spectral lines which proved the existence of interstellar matter!

Sunday, January 7 - On this night in 1610, Galileo discovered three of Jupiter's four largest satellites using his simple telescope. This revelation changed the face of a previously Earth-centered Universe. This morning before dawn, why not take out your binoculars and see if you, too, can discover the "Galilean moons" with simple equipment. You'll find the largest of all the planets in our solar system making a wonderful morning apparition along the ecliptic in Scorpius with Mars following behind!

Tonight let's return to Orion's "belt" and starting with just our eyes, look around a thumb's length south to discover an asterism of stars referred to as the "sword." On a clear, dark night away from city lights you can spot a glowing cloud of dust and gas surrounding Theta that has long held a place in astronomy history. It was first noted only one year after Galileo first used his telescope, and the discovery is credited to Nicholas Peiresc in 1611. It wasn't until Christian Huygens sketched it in 1656 that it became well known for containing a "heart of stars."

Now, take out your binoculars and have a look. Stars are still being born in a dense cloud behind the nebula, and hundreds of them are less than a million years old. Compared to our own Sun's age of over four billion years, these would seem almost new! But think again at what you are looking at...the light you see tonight left this area around 1900 years ago.

So magnificent are the many details that can be seen in the Orion Nebula, that chapter upon chapter could be devoted to its riches. For now, feast your eyes upon this 30 light-year expanse of dust, neutral and ionized hydrogen, and doubly-ionized oxygen illuminated by the ultraviolet starlight of this stellar nursery. It is more than 20,000 times larger than our own solar system and its mass could form 10,000 stars like our own Sun!


Until next week? May all your journeys be at light speed... ~Tammy Plotner.

PHOTO CREDIT:

http://higginsandsons.com/astro/Gassendi_a2_s1000_11-05-04.jpg

Gassendi - Credit: Wes Higgins